Apparatus for localized swaging of pipes



Dec. 20, 1966 A. GOEKE 3,292,414

APPARATUS FOR LOCALIZED SWAGING OF PIPES Filed Oct. 21, 1964 2 Sheets-Sheet l F/g. 7 9' 7a Fig. 2 a

INVENTOR ATTORNEY Dec. 20, 1966 A. GOEKE 3,292,414

APPARATUS FOR LOCALIZED SWAGING OF PIPES Filed Oct. 21, 1964 2 Sheets-Sheet 2 IINVENTOR AL FONS 6 o ewe ATTORNEY United States Patent 3 Claims. ((31. 72 402 The present invention relates to a method and apparatus for localized swaging, also known as setting down, of pipes. More particularly, the invention relates to a method and apparatus for providing comparatively thinwalled tubular blanks with swaged-down end portions to facilitate engagement of such end portions by draw-bench tongs or similar gripping devices when the blanks are subjected to one or more drawing operations.

It is well known to produce seamless pipe by sub ecting a tubular blank of ductile material to a series of consecutive drawing operations in a draw bench or the like. In order to enable the gripping mechanism to properly engage the end portion of a tubular blank prior to the start of the drawing operation, the end portion must be swaged down in such a way that it remains strong enough to withstand all tensional stresses which arise during drawing. It is normally desirable to provide the blank with a swageddown end portion whose diameter should not exceed the diameter of the ultimate product because such setting down enables the draw bench to perform two or more draws while its gripping mechanism engages the swageddown end portion. On the other hand, and in order to insure that the blank may be subjected to two or more consecutive drawing operations, it is necessary to make the end portion so strong that it can safely withstand all clamping and tensional stresses which arise during drawmg. It is equally desirable to set down the end portion of the blank in such a way that its axis coincides with the remainder of the blank and that it provides at least one passage for the flow of a fluid medium into and from interior of the blank. By making the swaged-down end portion coaxial with the remainder of the blank, the end portion may be readily introduced into and engaged by the gripping mechanism of a draw bench, and by providing at least one passage for fluid the swaged-down end portion will allow for evacuation of pickling liquid, tallow and other types of fluids which are used between consecutive drawing steps.

Serious problems arise in swaging down of thin-walled tubular blanks. The end portions of such blanks are normally too weak to withstand substantial clamping and tensional stresses which arise in the course of the second, third, etc. drawing operation. Thus, the end portion is likely to tear off or to be destroyed by excessive squeezing in response to'engagement with the gripping mechanism.

In order to avoid the likelihood of destruction, the end portions of thin-walled tubular blanks are often provided with corrugations which are separated by gaps so that the liquid is free to flow into and from the pipe. However, it was found that such types of corrugated end portions cannot withstand very high gripping stresses and are not satisfactory for repeated drawing. According to another proposal, the end portion of a thin-walled tubular blank is swaged down to be provided with a pair of bent-over portions, and the thus treated end portion is thereupon squeezed to form a body consisting of adjacent layers which completely seal the respective end. Of course, such blank is hard-to-handle because any liquid which has been admitted into its interior cannot escape through the end portion.

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Accordingly, it is an important object of the present invention to provide an improved method of swaging down end portions of seamless metallic pipes and similar tubular blanks in such a way that the end portions can withstand very high tensional and squeezing stresses but will allow for substantially unobstructed flow of liquid therethrou'gh without necessitating the provision of one or more drilled bores in the end portions.

Another object of the invention is to provide a method of the just outlined characteristics which may be used with particular advantage in connection with thin-walled tubular blanks which must undergo one but normally at least two or more drawing operations. In such thin-walled blanks, the wall thickness is a small fraction of the diameter.

A further object of the invention is to provide a method of setting down end portions of tubular blanks which consist of ductile material and which must be subjected to repeated action of redrawing dies because the depth of the desired draw is so great that the material may fracture if the shape change to ultimate wall thickness is attempted in a single draw.

An additional object of the invention is to provide a novel apparatus for the pracitce of my method and to construct the apparatus in such a way that the blanks may be provided with swaged-down end portions with little loss in time and with a high degree of uniformity.

Still another object of the invention is to provide an improved swaging die which may be used in the apparatus of the just outlined character.

Another object of the invention is to provide a swaging die which may be put to use in many types of presently known machine tools whereby such machine tools require minimal alterations to accommodate the die.

A concomitant object of the invention is to provide improved swaged-down end portions on seamless metallic pipes and similar tubular blanks so that such blanks may withstand very high tensional and other stresses when they undergo repeated drawing in a draw bench or a similar machine tool.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved swaging apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a side elevationalview of a tubular blank in the form of a seamless metallic pipe of ductile material one end portion of which has undergone partial deformation such as is necessary to set it down gradually to a desired diameter;

FIG. 1a is an end view of the structure shown in FIG. 1, looking downwardly;

FIG. 2 is another side elevational view of the blank and illustrates the next stage in the formation of a swageddown end portion;

FIG. 2a is an end view of the structure shown in FIG. 2, looking downwardly;

FIG. 3 is a side elevational view of the blank as it appears subsequent to completion of the swaging operation;

FIG. 3a is an end view of the blank, looking downwardly in FIG. 3;

FIG. 4 is an enlarged axial section through a swaging die which may be used to provide the blank of FIGS. 1 to 3a with a swaged-down end portion, the section being taken in the direction of arrows as seen from the line A-B in FIG. 5;

FIG. 4a is a transverse section as seen in the direction of arrows from the line CD of FIG. 4; and

FIG. is a front elevational view of a swaging apparatus which utilizes the swaging die of FIGS. 4 and 4a.

Briefly stated, one feature of the present invention resides in the provision of a method of setting down the ends of ductile tubular blanks preparatory to a drawing operation. The method comprises the steps of deforming at least three but preferably four or even more angularly spaced equidistant sections or zones at one end of the blank inwardly to provide axially extending corrugations whose depth decreases in a direction away from the corresponding end of the blank whereby the thus deformed length resembles the frusturn of a first hollow cone, and thereupon compressing the outer portion of the thus deformed length of the blank to immediately transform such outer portion into a substantially cylindrical body of constant cross section wherein the corrugations are flattened out or collapsed to form substantially radially extending equidistant twin-walled partitions defining between themselves a series of passages through which a fluid may flow into and from the interior of the blank. The remainder of the deformed length of the blank forms the frustum of a second hollow cone whose corrugations constitute extensions of twin-walled partitions on the outer portion. The innermost portions of the partitions may be and are preferably moved into actual abutment with each other along the axis of the outer portion whereby the partitions resist crushing of the outer portion in response to clamping forces transmitted by gripping instrumentalities which are used to connect the blank to the moving carriage of a draw bench when the blank is subjected to one or more drawing operations.

The corrugations may be formed by passing the blank through a composite annular swaging die which comprises inwardly extending projections. Once the blank is provided with such corrugations, the outer portion of the thus deformed length is forced into a second annular die or into an annular portion of the composite swaging die which causes the material of the outer portion to move inwardly whereby the corrugations are flattened and form the aforementioned partitions.

Referring first to FIGS. 4 and 4a, there is shown a composite annular swaging die 4 which comprises four arcuate segments in, 1b, 1c, 1d. These segments are assembled to form an annulus having a first portion which defines a conical bore 2 and a coaxial second portion which defines a cylindrical bore 3. The diameter of the conical bore 2 diminishes in a direction toward the cylindrical bore 3, and the latter communicates with the smaller-diameter end of the conical bore. The internal surface of the first portion whichforms the conical bore 2 is provided with four equidistant axially extending projections. Each such projection comprises a first semiconical portion whose tip is adjacent to the larger-diameter end of the bore 2 and a second semiconical portion 4b whose tip is adjacent to the inlet end of the bore 3. In many instances, the semiconical portions 41) may be dispensed with because the semiconical portions 4a will suflice to form the end portion of a tubular blank 6 with four equidistant corrugations 6a (see FIGS. 1-3a) by bending angularly spaced sections or zones of a blank radially inwardly. It is normally advisable to form the projections in the form of twin semiconical bodies 4a, 4b because such projections can be machined more readily than projections which merely comprise a single semiconical portion 4a.

FIG. 5 illustrates a swaging apparatus which utilizes the annular die 4 of FIGS. 4 and 4a. This apparatus comprises four radially reciprocable tool holders 9 each of which grips one of the segments la-ld. When the apparatus is not used for swaging down end portions of tubular blanks 6, the tool holders 9 may support other types of tools to carry out a swaging operation upon a piece of solid rod stock. Thus, the apparatus of FIG. 5 is useful to carry out a conventional swaging operation and also to provide thin-walled tubular blanks With swaged-down end portions. The mechanism including the parts for reciprocating the segments la-ld toward and away from the axes of the bores 2, 3 is well known in the art and forms no part of the present invention. The numeral 5 indicates the housing for the tool holders 9.

The apparatus of FIG. 5 operates as follows:

The leading end 6b of the tubular blank 6 shown in FIG. 1 is introduced into the conical bore 2, either by hand or by an automatic feeding mechanism not shown in the drawings. In the first stage of the swaging operation, a portion at the leading end 6b of the blank 6 is provided with angularly spaced axially extending corrugations 6a whose depth decreases in a direction away from the end 65. The end face of the blank 6 then resembles a cross with the walls of the corrugations 6a forming substantially V-shaped troughs. As the blank 6 continues to penetrate into the conical bore 2, the length of the corrugations 6a increases and the walls of each corrugation move nearer to each other, i.e., the corrugations are flattened out or collapsed in a manner as shown in FIGS. 2 and 2a whereby the innermost portions 6c of the corrugations may come in actual abutment with each other along. the axis of the blank 6. In FIG. 2, the corrugated length of the blank 6 forms the frustum of a hollow cone whose diameter diminishes in a direction away from the leading end 6b.

The blank 6 continues to penetrate into the annulus of segments 1a1d whereby the outer portion 8 of the frustum enters the cylindrical bore 3 and is compressed radially to form a cylindrical body of constant cross section which is ready to be gripped by the tongs on the carriage of a draw bench. The remainder 7 of the deformed length of the blank 6 forms a second conical frustum Whose axial length is determined by the axial length of the bore 2. In the entire cylindrical outer portion 8, the corrugations 6a are compressed to form twin-walled partitions defining between themselves four passages 6d which allow a liquid medium to flow into and from the interior of the blank 6. The outer portion 8 is capable of withstanding very high compressive and tensional stresses which arise when the blank 6 is subsequently treated in a draw bench to form a thin-walled pipe. During clamping, the innermost portions 60 of the twin-walled partitions will move in abut! ment with each other to ofiFer very high resistance to compression (crushing) of the outer portion 8. Of course, and as stated above, the innermost portions 6c of the partitions may move into actual abutment at the time the outer portion 8 is driven into the bore 3. The axis of the outer portion 8 coincides with the axis of the undeformed part of the blank 6, and its diameter is shown as approximating one-half of the diameter of the blank.

If desired, the blank may be formed with three, five or more twin-walled partitions, and each segment may consist of two portions whereby one portion of'each segment cooperates with the corresponding portions of the other segments to form the conical bore 2, and the other portion of each segment cooperates with the corresponding portions of the other segments to form the cylindrical bore 3. The projections 4a, 4b may be replaced by teeth which are adjustable radially of the annulus 4. The diameter of the bore 3 preferably equals or approximates the diameter of the thin-walled pipe which is obtained when the blank 6 Because the undergoes one or more drawing operations. outer portion of the swaged-down length of the blank 6 is shaped as a true cylinder, this outer portion may be introduced into the gripping mechanism of a draw bench with the help of automatic transfer devices. Also, such cylindrical outer portion can withstand very high compressive or crushing stresses and enables the blank to undergo a series of drawing operations without the formation of fissures.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a swaging apparatus, in combination, a die for setting down the ends of ductile tubular blanks preparatory to a drawing operation, said die comprising at least three arcuate segments movable radially with reference to each other and together forming an annulus including a first portion defining a conical bore having a larger-diameter end and a smaller-diameter end, and a second portion defining a cylindrical bore coaxial to and communicating with the smaller-diameter end of said conical bore, and at least one axially extending projection provided on each of said segments and extending substantially radially inwardly into said conical bore; and means for reciprocating said segments radially toward and away from each other to corrugate the leading end of a tubular blank which is introduced into and through the larger-diameter end of said conical bore, the outer portion of the thus deformed length of the blank being thereupon compressed radially inwardly to form a substantially cylindrical body on introduction into said cylindrical bore.

2. A structure as set forth in claim 1, wherein said projections are equidistant from each other and wherein each of said projections comprises a semiconical portion extending axially of said first portion and having a tip adjacent to the larger-diameter end of said conical bore.

3. In a swaging apparatus, in combination, a die for setting down the ends of ductile tubular blanks preparatory to a drawing operation, said die comprising at least three die members movable radially with reference to each other and each having a first portion carrying at least one axially extending projection protruding radially inwardly along a frustoconical surface having a larger-diameter end and a smaller-diameter end, and a second portion, said second portions defining a cylindrical bore coaxial to and communicating with the smaller-diameter end of said frustoconical surface; and means for reciprocating said die members radially toward and away from each other to corrugate the leading end of a tubular blank which is introduced through said larger-diameter end of said frustoconical surface between said axially extending radially inwardly protruding projections, the outer portion of the thus deformed length of the blank being thereupon compressed radially inwardly by said second portions of said die members so as to form a substantially cylindrical body.

References Cited by the Examiner UNITED STATES PATENTS 1,070,379 8/1913 Summey 72404 2,055,771 9/1936 McLaughlin 72368 3,154,978 11/1964 Baker 72402 FOREIGN PATENTS 672,439 10/1963 Canada. 576,747 5/1933 Germany.

567,355 2/1945 Great Britain.

OTHER REFERENCES German utility model, Reg. No. 1,881,506, October 1963.

JOHN F. CAMPBELL, Primary Examiner.

J. D. HOBART, Assistant Examiner, 

1. IN A SWAGING APPARATUS, IN COMBINATION, A DIE FOR SETTING DOWN THE ENDS OF DUCTILE TUBULAR BLANKS PREPARATORY TO A DRAWING OPERATION, SAID DIE COMPRISING AT LEAST THREE ARCUATE SEGMENTS MOVABLE RADIALLY WITH REFERENCE TO EACH OTHER AND TOGETHER FORMING AN ANNULUS INCLUDING A FIRST PORTION DEFINING A CONICAL BORE HAVING A LARGER-DIAMETER END AND A SMALLER-DIAMETER END, AND A SECOND PORTION DEFINING A CYLINDRICAL BORE COAXIAL TO AND COMMUNICATING WITH THE SMALLER-DIAMETER END OF SAID CONICAL BORE, AND AT LEAST ONE AXIALLY EXTENDING PROJECTION PROVIDED ON EACH OF SAID SEGMENTS AND EXTENDING SUBSTANTIALLY RADIALLY INWARDLY INTO SAID CONICAL BORE; AND MEANS FOR RECIPROCATING SAID SEGEMENTS RADIALLY TOWARD AND AWAY FROM EACH OTHER TO CORRUGATE THE LEADING END OF A TUBULAR BLANK WHICH IS INTRODUCED INTO AND THROUGH THE LARGER-DIAMETER END OF SAID CONICAL BORE, THE OUTER PORTION OF THE THUS DEFORMED LENGTH OF THE BLANK BEING THEREUPON COMPRESSED RADIALLY INWARDLY TO FORM A SUBSTANTIALLY CYLINDRICAL BODY ON INTRODUCTION INTO SAID CYLINDRICAL BORE. 